Neither the Jedi nor the council suspected Merrik's allegiance to the Separatists, and he managed to smuggle a large box in the cargo bay containing multiple assassin probes, which he planned to use in the assassination of the Duchess. Merrik, along with the other senators, stood in Satine's quarters as she discussed her disapproval of the Galactic Republic's desire to occupy Mandalore with their armies as a way of defense. As Satine and General Kenobi got into a heated argument about the necessity of violence, both Merrik and Orn Free Taa suggested that they put aside politics and satisfy the long trip with dinner.

While a team of clone troopers was sent to check the cargo bay, Merrik secretly activated the probes, which proceeded to kill much of the troopers and search for a way out to the upper levels of the ship. They were programmed to attack the Duchess and all who protected her, leaving Merrik himself the only one safe from harm. Skywalker soon went down to the cargo bay to aid in the clones' investigation, and encountered the probes as the senators and Kenobi sat at dinner. One probe was defeated by the Jedi and clones, while another managed to get to the upper levels and attempted to kill the senators. Despite the droids' power, the Jedi managed to destroy them both.

After the hostile probes were deactivated, Merrik's fail-safe kicked in: dozens of probe killers emerged from the dead droids and continued the attack. Still, the combined efforts of the Jedi and clones managed to destroy the small droids. As the senators attempted to get on with dinner, Skywalker went to find how the box with the probes had managed to get on the ship. He checked with the service droid in charge of the ship's manifest and found that the box had been allowed to go in the cargo because it bore a senate stamp. With this information, Skywalker and Kenobi deduced that one of the senators was a traitor.

Merrik takes Duchess Satine hostage.

Kenobi discovered a surviving probe killer, and trapped it under a glass dome on a platter. He knew that the droid would attempt to kill any senator other than the turncoat, and brought it to the dinner table to test his theory. The droid displayed hostility toward all of the council members, save Merrik. The prince then took the still moment to knock the trapped droid out of the Jedi's hands, releasing it while at the same time admitting to Kenobi's cleverness. The probe then went loose, attacking all in the room except for Merrik, but was destroyed by Kenobi. Merrik used the confusion to draw a blaster and take Kryze hostage.

The senator dragged his hostage down the hall to the bridge, where he killed the pilots, despite the captain's pleas for mercy. This lack of mercy prompted Satine to label Merrik a "horrid monster," to which Merrik replied with "Get used to it". Merrik used the communications system to contact Death Watch command. Reporting his success in capturing Duchess Satine, Merrik stood by as Pre Vizsla sent reinforcements—a trio of Droch-class boarding ships—to the Coronet. Super battle droids infiltrated the ship and began a firefight with the clones and Duchess Satine's guards.

Merrik took the precaution of wiring the ship's engines to explode upon detonation, even ready to kill himself if it meant accomplishing his mission. Soon after, Kenobi found the captor and captive, and followed them closely as Merrik retreated to the boarding ships. Meanwhile, Skywalker and his men managed to defeat the last of the droids, and the Knight swiftly went to locate Kenobi. Merrik contacted the droids and signaled them to prepare to disengage the enemy. Ready to board a nearby ship, Merrik told Satine to say farewell to Kenobi. The Duchess and Jedi then admitted their love for one another, as they believed they would not meet again.

Tal Merrik's death.

Merrik expressed his disgust toward the romantic scenario, and this allowed Kryze to catch him off guard: she stepped on his foot to break free of his grasp, gaining possession of his blaster in the process. She referred to him as one with the romantic soul of a slug, and pointed out that "slugs are so often trod upon." Impressed by the turnabout, Merrik pointed out that he would still be victorious no matter what. He intended to escape and destroy the Coronet, accomplishing his goal regardless of not having the Duchess captive. Kryze declared she would not allow such an event, but Merrik doubted her ability to stop him.

The senator mocked his would-be murderer, as he knew that if she killed him, she would be regarded as a hypocrite to all her pacifist ideals. He also mocked Kenobi, whom the duchess would look down upon if he killed him. Merrik goaded either of the two, who had Merrik at their mercy, to strike first and "brand themselves a cold-blooded killer." Confident that neither would be able to kill him without destroying everything they stood for, Merrick's look of smug victory turned to that of bewildered pain when he was suddenly stabbed in the chest from behind by Skywalker with his lightsaber, killing the treacherous Senator. Kenobi was rather disappointed, yet not surprised, by Skywalker's move. Skywalker casually replied with "What? He was gonna blow up the ship."

"That is touching. Truly, it is. But it's making me sick, and we really must be going!""You have the romantic soul of a slug, Merrik! And slugs are so often trod upon!"

―Merrik and Satine, after the latter's confession of love toward Obi-Wan Kenobi[src]

Merrik was known to use other people to achieve his own goals and put on an air of gentleness to fool them. He managed to sneak three assassin probes and their probe killer complements into the Coronet, and used a Senate stamp rather than a signature to prevent anyone from knowing of his involvement. This did backfire on him, though, as Skywalker and Kenobi managed to narrow it down, and after a captured probe killer acted calm in sharp contrast to the hostility it displayed towards the other three senators, his allegiance was revealed, but he still managed to take Satine hostage.

Merrik was a very tactical, calculating individual, always anticipating what would happen next, taking extra precaution by wiring the Coronet's engines to explode, and ensuring the best odds would turn in his favor; he also constantly reminded Satine and Kenobi of his forms of leverage, gloating that he had the edge. He was as ruthless as his superior, and shot all four of the weaponless commandos on the bridge, and murdered the captain even after the man attempted to plead with him. This led to Satine calling him a "horrid monster," to which Merrik told her to "get used to."

He also showed an open disgust for the romance between Satine and Kenobi. His distraction of insulting the display of love caused him to lose his hostage and brought him further to defeat. In his final moments, he enjoyed taunting both Kenobi and Satine, taking pleasure from reminding them of the horrible things that held them back from murdering him in cold-blood.